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If Drs. Vinay Prasad and Tracy Hoeg want to prove they actually care about routine vaccines, they can do what the should have done a long time ago and openly and unequivocally denounce Mr. Kennedy and his fire hose of anti-vaxx disinformation.

The post A Simple Challenge For Drs. Vinay Prasad and Tracy Hoeg: Denounce Robert Kennedy Jr. For Promoting The Movie Vaxxed 3: Authorized to Kill first appeared on Science-Based Medicine.

Computers truly are wonderful things and powerful but only if they are programmed by a skilful mind. Check this out… there is an algorithm that mimics the growth of slim mold but a team of researchers have adapted it to model the large scale structure of the Universe. Since the Big Bang, the universe has been expanding while gravity concentrates matter into galaxies and clusters of galaxies. Between them are vast swathes of empty space called voids. The structure, often referred to as the cosmic web.

The cosmic web is the largest scale structure of the universe and it’s made up of filaments of galaxies and dark matter that stretch across the gulf of space. The filaments connect galaxy clusters with immense voids in between. The web-like structure has formed as a result of the force of gravity pulling matter together since the beginning of time. Studying the cosmic web helps us to piece together the evolution of the universe, how matter is distributed and the relationship with dark matter. 

Image from NASA’s Hubble Space Telescope of a galaxy cluster that could contain dark matter (blue-shaded region). (Credit: NASA, ESA, M. J. Jee and H. Ford et al. (Johns Hopkins Univ.))

Since the early 80’s it’s been known that the nature of a galaxy and its environmental properties has an impact on how it grows and evolves. The exact nature and how this happens is still the cause of many debates. A team of researchers believe they may have demonstrated how galaxies evolve using a slime algorithm!

The team, led by Farhanul Hasan, Professor Joe Burchett and eight co-authors, published their findings ‘Filaments of the Slime Mold Cosmic Web and How they Affect Galaxy Evolution’ in August’s edition of the Astrophysical Journal.  In the paper they report how the mold algorithm has helped to unlock mysteries of the cosmos. 

Burchett recommended the slime mold algorithm could be used for an astrophysical application. Hasan worked with Burchett and altered the algorithm to help them visualise the cosmic web. The team worked with graphics rendering expert Oskar Elek to use the slime mold algorithm. The mold algorithm was designed to mimic slime mold that could find its own food by reforming itself into a structure much like the cosmic web. It took the team several years to complete their work. 

In shaping the Universe, gravity builds a vast cobweb-like structure of filaments tying galaxies and clusters of galaxies together along invisible bridges hundreds of millions of light-years long. A galaxy can move into and out of the densest parts of this web throughout its lifetime. Credit: Volker Springel (Max Planck Institute for Astrophysics) et al.

The result produced far more detailed discrete structures than the old method according to Hasan. He added ‘I didn’t know how well it was going to work or not work, but I had a hunch the slime mold method could tell us much more detailed information about how density is structured in the universe, so I decided to give it a try.’

Of the conclusion, Hasan and team found that the impact on galaxies seems to have taken the proverbial u-turn. In earlier epochs, the growth of a galaxy was stimulated by proximity to larger structures. In the near universe, and therefore in cosmologically recent times, we see that galaxy growth is limited by proximity to larger structures. This wasn’t possible without the modified slime mold algorithm. We can now map out the gas around the real universe using the algorithm across many different times to help understand how the web has changed and the universe evolved. 

Source : NMSU astronomy research uses slime mold to model galaxies

The post Slime Mold Can Teach Us About the Cosmic Web appeared first on Universe Today.

By staring into the hellish landscape of Jupiter's moon Io -- the most volcanically active location in the solar system -- astronomers have been able to study a fundamental process in planetary formation and evolution: tidal heating.

Photosynthesis changed Earth in powerful ways. When photosynthetic organisms appeared, it led to the Great Oxygenation Event. That allowed multicellular life to evolve and resulted in the ozone layer. Life could venture onto land, protected from the Sun’s intense ultraviolet radiation.

But Earth’s photosynthetic organisms evolved under the Sun’s specific illumination. How would plants do under other stars?

Our Sun is a G-type star, sometimes called a yellow dwarf. It seems like a normal star to us, but yellow dwarfs aren’t that common. Only about 7% to 8% of stars in the Milky Way are G-type stars. When it comes to understanding habitability on exoplanets, we need to understand the more plentiful types of stars.

Some scientists propose that K-dwarf stars are the most optimal host stars for habitable exoplanets. They’re between about 50% and 80% as massive as G-type stars, are more abundant and have stable luminosities for billions of years longer than Sun-like stars. The Sun will be stable on the main sequence for about 10 billion years, while K-type stars can be stable for up to 70 billion years. Despite this, much exoplanet habitability research focuses on M-dwarfs, or red dwarfs, which may actually be far more inhospitable to life because of flaring and tidal locking.

In a new study, a trio of researchers simulated the light output from a K-dwarf star and grew two photosynthetic organisms in those conditions to see how they responded. The research article is “Observation of significant photosynthesis in garden cress and cyanobacteria under simulated illumination from a K dwarf star.” It’s published in the International Journal of Astrobiology, and the lead author is Iva Vilovi?, a PhD student in the Astrobiology Research Group at the Technical University of Berlin.

These figures from the article show the spectra for both the Sun and a K-dwarf star, and the simulated spectra for both. Image Credit: Vilovi? et al. 2024.

Garden cress, whose Latin name is Lepidium sativum, is a common garden green used in salads, soups, and sandwiches. It’s an adaptable plant that grows rapidly. The cyanobacterium Chroococcidiopsis is an extremophile known for lying dormant for 13 million years and remaining viable. It can resist radiation, desiccation, and extreme temperatures and is of interest in astrobiology.

We expect photosynthesis to play a role in astrobiology. Starlight provides the energy for organisms to synthesize organic compounds. In order to understand photosynthesis in astrobiology, we need to understand how other stars could power photosynthesis. “Therefore, understanding any planet in the context of its stellar environment is an essential step in assessing its habitability,” the authors write.

Astronomers search for Earth-like planets around Sun-like stars because that’s the only life we know of. They also pay special attention to M-dwarfs because they’re so plentiful and are known to host many rocky exoplanets in their habitable zones. Scientists have demonstrated that photosynthetic organisms from Earth can grow under simulated M-dwarf light. But M-dwarf habitability faces a whole host of potential barriers.

Artist’s impression of a flaring red dwarf star orbited by an exoplanet. Red dwarfs can flare violently, which could make planets in their habitable zones unable to support life. Planets in their habitable zones are also often tidally locked, which is another barrier to habitability. Credit: NASA, ESA, and G. Bacon (STScI)

In this work, the researchers focused on K-dwarfs. They lack the magnetic activity that appears to generate extremely powerful flaring on M-dwarfs, flaring so powerful that it could sterilize planets in their liquid-water habitable zone. The habitable zones around K-dwarfs are also far enough away that planets wouldn’t be tidally locked, another potential barrier to habitability that affects M-dwarfs. K-dwarfs also become habitable sooner in their lives than M-dwarfs due to their rapidly weakening FUV and X-ray fluxes.

“All things combined, K dwarfs can be considered the ‘Goldilocks stars’ in the search for potentially life-bearing planets,” the authors write.

This table from the research article shows the conditions that the researchers recreated in their study. Image Credit: Vilovi? et al. 2024.

The trio of researchers exposed watercress seedlings to three different light regimes: sunlight, K-dwarf light, and no light. Visually, the solar and K-dwarf samples were similar, though most of the time, the seeds sprouted a day or two earlier than under solar light. The K-dwarf sample also had marginally larger leaf surface area.

The researchers grew garden cress (Lepidium sativum) on a sand substrate with one hundred initial seedlings under Solar (effective temperature 5800 K), K dwarf (effective temperature 4300 K) and dark conditions. This image shows the visual results for selected days. Garden cress under K dwarf radiation sprouts sooner relative to Solar and dark conditions. Image Credit: Vilovi? et al. 2024.

After seven days, a side view of the samples showed that height and stem elongation were different. Under the K-dwarf lighting, the watercress grew taller.

The watercress grew taller under K-dwarf lighting than under Solar conditions. Image Credit: Vilovi? et al. 2024.

The researchers also measured water content and dry mass. Under K-dwarf conditions, the watercress had slightly higher water content, while the dry content was lower compared to solar conditions.

These figures show the water content and dry content for all three garden cress samples. Image Credit: Vilovi? et al. 2024.

The researchers also tested the photosynthetic efficiency and found no significant difference between the solar and K-dwarf samples.

The hardy extremophile Cyanobacterium Chroococcidiopsis sp. CCMEE 029 is at the other end of the spectrum from the quick-growing garden cress. It’s a survivor that can withstand long periods of dormancy and extreme growing conditions. The researchers also cultivated it under Solar, K-dwarf and dark conditions.

They measured the average integrated density (IntD) of the cyanobacterium, which is an indicator of culture growth. They found that the K-dwarf sample exhibited higher values than the solar sample, but the differences were not considered significant. Predictably, “Cyanobacteria under constant dark conditions failed to exhibit significantly measurable IntD,” the authors write in their paper.

This figure from the research article shows incremental ratios and integrated densities of the cyanobacterium on selected days under Solar, K dwarf and dark conditions. Though the integrated density was higher under K-dwarf conditions, the difference isn’t significant, according to the researchers. Image Credit: Vilovi? et al. 2024.

They point out that their study didn’t replicate natural conditions completely. Sunlight intensity changes throughout the day, but they didn’t include that in their study. “Sunlight intensity on Earth varies throughout the day, with peak intensities occurring during the central hours. This variation is crucial for plants to adapt and respond to changing light conditions, including the activation of non-photochemical quenching (NPQ) to mitigate the effects of excess light,” they write. NPQ helps plants cope with periods of excess light, meaning light above what it can photosynthesize, by dissipating it as heat.

“Understanding the effects of K-dwarf radiation on photosynthesis and growth is of foremost importance not only for the assessment of its viability for phototrophic organisms but also for the interpretation of atmospheric biosignatures outside of the Solar System,” the authors explain. Other research in this area has focused on M-dwarfs, and this trio of researchers say that to the best of their knowledge, theirs is the first to look at photosynthesis and K-dwarfs.

“These results can bring us closer to addressing which stellar environments could be the optimal candidates in the search for habitable worlds,” the authors write. “These findings not only highlight the coping mechanisms of photosynthetic organisms to modified radiation environments but also they imply the principal habitability of exoplanets orbiting K dwarf stars.”

The post Plants Would Still Grow Well Under Alien Skies appeared first on Universe Today.

On September 15th, 2024, the Polaris Dawn crew returned to Earth after spending five days in orbit. The mission was the first of three planned for the Polaris program, a private space project to advance human spaceflight capabilities and raise funds and awareness for charitable causes. The mission’s Dragon spacecraft safely splashed down off the coast of Florida at 3:36:54 a.m. EDT (12:36:54 p.m. PDT). Once their spacecraft was retrieved, the crew was flown to the Kennedy Space Center to see their families and undergo medical examinations before traveling to Houston to complete more of the mission’s studies.

The mission accomplished several objectives, including flying higher than any previous crewed mission since the Apollo Era – 1,408 km (875 mi) above the Earth’s surface, or three times the altitude of the International Space Station (ISS). The mission passed through the Van Allen Radiation Belt to learn more about the effects of space radiation on human physiology. For starters, the mission included the first-ever commercial spacewalk, performed by mission commander Jared Isaacman when the spacecraft was 700 km (435 mi) above Earth.

This feat also tested SpaceX’s new Extravehicular Activity Spacesuit (EVA), designed for long-duration spaceflight and operations on the lunar and Martian surface. Other experiments included Starlink’s laser-based communications system, which is essential for future missions to the Moon, Mars, and beyond. This consisted of the crew sending signals between optical links on the Dragon spacecraft and Starlink satellites. The crew also carried out 36 other science experiments, in collaboration with 31 global institutions, designed to advance human health and space exploration.

The mission also featured a special reading of Kisses from Space, written by Anna Menon (Polaris Dawn’s mission specialist and medical officer) and Keri Vasek. The event was live-streamed and showed Menon sharing her book with her family and many patients at St. Jude Children’s Research Hospital – one of the charitable organizations supported by the Polaris Program. The mission also had a “music moment,” where mission specialist Sarah Gillis played “Rey’s Theme” on the violin from The Force Awakens composed by John Williams.

The recording was back to Earth via Starlink, where it was accompanied by professional and youth musicians from around the world through a series of pre-recorded orchestra sessions. The combined footage was used to create the video “Harmony of Resilience” in support of St. Jude Children’s Research Hospital and El Sistema USA, a charity dedicated to providing access to music education for all children. Additional updates about the mission and crew post-return will continue to be available via Polaris’ official X account, Instagram, and their website. 

The second flight in the Polaris Program will see another crewed Dragon spacecraft launching to orbit and conducting additional experiments to advance human spaceflight, in-space communications, and scientific experiments. The launch date for this mission is currently TBD. The third mission (also TBD) will be the first crewed spaceflight using SpaceX’s Starship and Superheavy launch system.

Further Reading: Polaris Program

The post The Polaris Dawn Crew is Back on Earth appeared first on Universe Today.

As someone that has always lived in the UK countryside I am no stranger to the glory of a dark star-filled sky. Sadly 60% of the world’s population has already lost access to the night sky thanks to light pollution. Across Europe and the US that number climbs to nearer 80%. A team of researchers want to try and track the growth of light pollution and to that end have developed an inexpensive sensor made from “off-the-shelf” parts. Their hope is that people around the world will build and install these sensors to share their data enabling them to track the spread of light pollution. If you’ve got technical skills, this could be a fun project.

Astronomers the world over are all too familiar with the scourge of light pollution. It’s one of the main reasons observatories tend to be located in the middle of nowhere. Of course the night sky is illuminated by natural light from the stars and Moon but also zodiacal light and aurora can shed their own mystical light on our sky. Light pollution doesn’t refer to these natural wonders, instead it refers to the excessive or misdirected artificial light from human activity. 

Urban sprawl and accompanying light pollution is an issue for both astronomers and fireflies. This view shows the light dome from the city of Duluth, Minn. 20 miles north of town. It erases the dark skies. Credit: Bob King

Light pollution not only effects astronomers but it disrupts ecosystems, wildlife and even human health. It typically comes from streetlights, building lighting, advertising and even car headlights. It generally creates a nasty orange or white glow that hangs over towns and cities obscuring the beauty of the universe. It also interferes with with the behaviour of nocturnal animals, has a negative impact on human sleep cycles and can lead to health issues like insomnia or stress. There are suitable ways external lighting can be controlled and its impact minimised but we need to get people to actually want to make that change. 

An annotated light pollution map for Nebraska. Credit: Dave Dickinson/The Light Pollution Atlas.

That’s the dream of the team behind the FreeDSM device and the Gaia4Sustaniability project. Their aim is to provide an easy to use piece of hardware and software which is reliable and will be able to measure night sky brightness caused by light pollution. The framework will be able to calculate the excess light pollution which is in excess of natural sky brightness to inform public, non-scientific stakeholders and the science community about the spread of light pollution.

Using hardware that is readily available the device is relatively cheap to build coming in at less than $65 USD (around £50 GBP.) It is based around the Osram TSL2591 sensor with two diodes.  One of them takes sky brightness measurements in the infrared and the other in the full visible spectrum. It then samples the brightness every minute while it also captures humidity and temperature. Looking at the relatively comprehensive instructions it looks like anyone with modest DIY skills will be able to build this. 

The device is an excellent step forward toward analysing the state of light pollution across the planet. It uses data from the Gaia satellite to greatly enhance the accuracy of the light pollution measurements. It does require legions of groups or individuals to build and install a device however. Hopefully it will appeal to the several thousands of fellow geeks out there   to pick up their screwdriver and soldering iron to make the dream of turning the tide on light pollution a reality.

If you want to have a go for yourself then you can learn more about the project here and find the instructions to build your own sensor here

Source : FreeDSM and the Gaia4Sustaniability project: a light pollution meter based on IoT technologies

The post Building a Worldwide Map of Light Pollution appeared first on Universe Today.

Nearly imperceptible quantum flickers used to limit how precisely we could detect the way space-time ripples, but squeezing the laser light used in detectors overcomes this and doubles the number of gravitational waves we can see

The average surface temperature varied more widely and was even hotter than previously thought during much of the past 500 million years, according to the most rigorous study so far

The Sun is midway through its life of fusion. It’s about five billion years old, and though its life is far from over, it will undergo some pronounced changes as it ages. Over the next billion years, the Sun will continue to brighten.

That means things will change here on Earth.

As the Sun goes about its business fusing helium into hydrogen, the ratio of hydrogen to helium in its core changes. Over time, the core slowly becomes more enriched in helium. As helium accumulates in its core, the core’s density increases, meaning protons are more closely packed together. That creates a situation where the Sun can fuse hydrogen more efficiently. After a chain reaction of processes and cause and effect, the end result is that the Sun’s luminosity increases. The Sun’s luminosity has already increased by about 30% since its formation, and the brightening will continue.

Any increase in the Sun’s luminosity can have a pronounced effect on Earth. Environmental cycles like the carbon, nitrogen, and phosphorous cycles sustain Earth’s biosphere. As the Sun becomes brighter, it will affect these cycles, including the carbonate-silicate cycle, which moderates the accumulation of carbon dioxide (CO2) in the planet’s atmosphere.

This schematic shows the relationship between the different physical and chemical processes that make up the carbonate-silicate cycle. In the upper panel, the specific processes are identified, and in the lower panel, the feedbacks associated are shown; green arrows indicate positive coupling, while yellow arrows indicate negative coupling. Image Credit: By Gretashum – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=79674633

Scientists think that over the next billion years, the brightening Sun will disrupt this cycle, leading to declining CO2 levels. Plants rely on CO2 and the levels are expected to plummet, which means that complex land life would end in the next billion years.

It’s a bleak prognosis, but new research suggests it might not happen.

The new research is “Substantial extension of the lifetime of the terrestrial biosphere,” and it’s been accepted for publication in the Planetary Science Journal. It’s in pre-print now, and the lead author is R.J. Graham, a postdoctoral researcher in the Department of Geophysical Sciences at the University of Chicago.

“Approximately one billion years (Gyr) in the future, as the Sun brightens, Earth’s carbonate-silicate cycle is expected to drive CO2 below the minimum level required by vascular land plants, eliminating most macroscopic land life,” the authors write.

As stars like our Sun age, they become brighter and warmer. Image Credit: ESO/L. Calçada

As the Sun brightens and warms the Earth’s surface, scientists expect the carbonate-silicate cycle to draw more CO2 out of the atmosphere because of carbonate-silicate weathering and carbonate burial. Rainwater is enriched with atmospheric carbon, which reacts with silicate rocks and breaks them down. The products of the chemical reactions that break them down find their way to the ocean floor, where they form carbonate minerals. As these minerals are buried, they effectively remove carbon from the atmosphere.

Normally, the cycle acts as Earth’s natural thermostat. However, higher temperatures make the reactions more efficient, meaning the carbonate-silicate cycle will remove more CO2 from the atmosphere. That’s what led scientists to conclude that the CO2 will become so low that planet life will perish. However, the authors examined these ideas and found that it may not quite work out that way.

“Here, we couple global-mean models of temperature- and CO2-dependent plant productivity for C3 and C4 plants, silicate weathering, and climate to re-examine the time remaining for terrestrial plants,” they write. C3 and C4 plants are two main plant groups that are classified based on how they perform photosynthesis and absorb carbon. They’re relevant because they respond differently to higher temperatures.

The researchers say recent data shows that the carbonate-silicate cycle isn’t as temperature-dependent as previously thought. Instead, it’s only weakly temperature-dependent and more strongly CO2-dependent. In that case, “we find that the interplay between climate, productivity, and weathering causes the future luminosity-driven CO2 decrease to slow and temporarily reverse, averting plant CO2 starvation,” they explain.

Instead of a one billion-year outlook for Earth’s plant life, the researchers say atmospheric CO2 levels will mean plants have another 1.6-1.86 billion years. When plants can no longer survive, it won’t be because of plummeting CO2 levels. Instead of CO2 starvation, it’ll be because of what scientists call the moist greenhouse transition.

When that transition happens, a planet’s atmosphere becomes saturated with water vapour as the planet warms. Since water vapour is a potent greenhouse gas, it creates a feedback loop of increased warming. Eventually, it’s simply too hot for plants to survive. The consequences don’t end there. As the Earth’s upper atmosphere becomes more saturated with water vapour, UV energy splits water apart, and the hydrogen drifts off into space. In this situation, there’s a gradual and irreversible loss of water into space.

According to the authors, Earth won’t experience this transition for between about 1.6 and 1.86 billion years.

This astronaut photograph shows the sky over the Amazon Basin during the rainy season. Image Credit: NASA

“We show that recent data indicating weakly temperature-dependent silicate weathering lead to the prediction that biosphere death results from overheating, not CO2 starvation,” the authors write. “These findings suggest that the future lifespan of Earth’s complex biosphere may be nearly twice as long as previously thought.”

These results also affect our understanding of exoplanet habitability. It has to do with what are called ‘hard steps’ in the appearance and evolution of life. The hard steps model says that certain evolutionary transitions were difficult and unlikely to happen twice. Some examples are the appearance of multicellular organisms and the Cambrian explosion.

But if Earth’s biosphere has a much longer lifespan than thought, that affects the hard steps model.

“A longer future lifespan for the complex biosphere may also provide weak statistical evidence that there were fewer “hard steps” in the evolution of intelligent life than previously estimated and that the origin of life was not one of those hard steps,” the authors conclude.

If that’s the case, then exoplanet habitability could be less rare than thought.

The post Life Might Thrive on the Surface of Earth for an Extra Billion Years appeared first on Universe Today.

Genetic testing on samples collected during the earliest days of the covid-19 outbreak suggests it is likely that the virus spread from animals to humans at the Huanan seafood market

Scientists are now able to directly compare the different kinds of injury that mechanical ventilation causes to cells in the lungs. In a new study, using a ventilator-on-a-chip model, researchers found that shear stress from the collapse and reopening of the air sacs is the most injurious type of damage.

Researchers have developed a Martian atmospheric evolution model to propose a new theory about Mars's past.

A meta-analysis of 137 clinical trials finds triptan drugs are among the most effective for treating migraines, while newer ditan and gepant drugs were rated less highly

Most of the exoplanets we’ve discovered orbit red dwarf stars. This isn’t because red dwarfs are somehow special, simply that they are common. About 75% of the stars in the Milky Way are red dwarfs, so you would expect red dwarf planets to be the most abundant. This also means that most habitable worlds are going to orbit these small, cool stars, and that has some significant consequences for our search for life.

To begin with, any potentially habitable red dwarf world will need to orbit their star closely, just to be warm enough for things like liquid water. The TRAPPIST-1 system I talked about yesterday is a good example of this. The three potentially habitable planets of the system orbit at a small fraction of the distance between Mercury and the Sun. This means they are at risk of things such as stellar flares, but it also means they are almost certainly tidally locked.

Tidal locking occurs when a planet or moon is so close to its companion that tidal forces cause its rotation to sync with its orbital motion. When a planet is tidally locked, one side always faces its star while the other side is forever in darkness. As you might imagine, this would mean the warm side fries while the other freezes. That’s true unless the planet were to have a good atmosphere. With a water-rich Earth-like atmosphere heat could move between the day and night sides. Weather would be strange on such a world, but a tidally locked world could be habitable, with fairly even day-side and night-side temperatures.

How clouds could make a planet appear airless. Credit: Powell, et al

Observing the atmospheres of tidally locked planets is difficult, but astronomers have a trick to see whether an atmosphere exists. Rather than trying to capture an atmospheric spectra, they can simply measure the surface temperature of the planet on opposite sides. So, look at the star as the planet moves in front of it to determine the temperature of the dark side, and look at it again as the planet moves behind the star to get the light side temperature. If the dark and light sides have dramatically different temperatures, then it must not have an atmosphere. Easy-peasy. But a new study shows that isn’t necessarily true.

In this paper the authors argue that clouds on the dark side of a world could skew our data. To show this, they considered a tidally locked world with a thick atmosphere. Based on their models, the atmosphere would moderate global temperatures on the planet so that the day side is only a few dozen degrees warmer than the dark side. This is similar to the day and night extremes of a dry region on Earth. While moderate, the temperature shift would be enough to trigger the formation of thick clouds on the dark side.

In this scenario, the day side would be mostly cloudless and we would measure the warm temperature of the planet’s surface. But with a cloudy dark side we would measure temperature of the upper layer of clouds, which would be much colder. So even though surface temperatures of the planet are fairly uniform, it would appear to have an extreme temperature shift like an airless world. The authors go on to look at how observations from the JWST could distinguish between cloudy planets and those without an atmosphere, but it is clear that one simple trick in the search for habitable planets isn’t quite so simple.

Reference: Powell, Diana, Robin Wordsworth, and Karin Öberg. “Nightside Clouds on Tidally-locked Terrestrial Planets Mimic Atmosphere-Free Scenarios.” arXiv preprint arXiv:2409.07542 (2024).

The post Exoplanets Could be Hiding Their Atmospheres appeared first on Universe Today.

Back in April 2022, the CDF experiment, which operated at the long-ago-closed Tevatron particle collider. presented the world’s most precise measurement of the mass of the particle known as the “W boson“. Their result generated some excited commentary, because it disagreed by 0.1% with the prediction of the Standard Model of particle physics. Even though the mismatch was tiny, it was significant, because the CDF measurement was so exceptionally precise. Any disagreement of such high significance would imply that something has to give: either the Standard Model is missing something, or the CDF measurement is incorrect.

Like most of my colleagues, I was more than a little skeptical about CDF’s measurement. This was partly because it disagreed with the average of earlier, less precise measurements, but mainly because of the measurement’s extreme challenges. To quote a commentary that I wrote at the time,

• “A natural and persistent question has been: “How likely do you think it is that this W boson mass result is wrong?” Obviously I can’t put a number on it, but I’d say the chance that it’s wrong is substantial. Why? This measurement, which took several many years of work, is probably among the most difficult ever performed in particle physics. Only first-rate physicists with complete dedication to the task could attempt it, carry it out, convince their many colleagues on the CDF experiment that they’d done it right, and get it through external peer review into Science magazine. But even first-rate physicists can get a measurement like this one wrong. The tiniest of subtle mistakes will undo it.”

In the weeks following CDF’s announcement, I attended a detailed presentation about the measurement. The physicist who gave it tried to convince us that everything in the measurement had been checked, cross-checked, and understood. However, I did not find the presentation exceptionally persuasive, so my confidence in it did not increase.

But so what? It doesn’t matter what I think. All a theorist like me can do, seeing a measurement like this, is check to see if it is logically possible and conceptually reasonable for the W boson mass to shift slightly without messing up other existing measurements. And it is.

(In showing this is true, I took the opportunity to explain more about how the Standard Model works, and specifically how the W boson’s mass arises from simple math, before showing how the mass could be shifted upwards. Some of you may still find these technical details interesting, even though the original motivation for this series of articles is no longer what it was.)

Instead, what really matters is for other experimental physicists to make the same measurement, to see if they get the same answer as CDF or not. Because of the intricacy of the measurement, this was far easier said than done. But it has now happened.

In the past year, the ATLAS collaboration at the Large Hadron Collider [LHC] presented a new W boson mass measurement consistent with the Standard Model. But because their uncertainties were 60% larger than CDF’s result, it didn’t entirely settle the issue.

Now the CMS collaboration, ATLAS’s competitor at the LHC, has presented their measurement. They have managed to be almost as precise at that of CDF — a truly impressive achievement. And what do they find? Their result, in red below, is fully consistent with the Standard Model, shown as the vertical grey band, and with ATLAS, the bar line just above the red one. The CDF measurement is the bar outlying to the right; it is the only one in disagreement with the Standard Model.

Measurements of the W boson mass made by several different experiments, with names listed at left. In each case, the dot represents the measurement and the horizontal band represents its uncertainty. The vertical grey band represents the Standard Model prediction and its own uncertainty. The ATLAS and CMS measurements, shown at the bottom, agree with each other and with the Standard Model, while both disagree with the CDF measurement. Note that the uncertainty in the CMS measurement is about the same as in the CDF measurement.

Since the ATLAS and CMS results are both consistent with all other previous measurements as well as with the Standard Model, and since CMS has even reached the same level of uncertainty obtained by CDF, this makes CDF by far the outlier, as you can see above. The tentative but reasonable conclusion is that the CDF measurement is not correct.

Of course, the CDF experimentalists may argue that it is ATLAS and CMS that have made an error, not CDF. One shouldn’t instantly dismiss that out of hand. It’s worth remembering that ATLAS and CMS use the same accelerator to gather their data, and might have used similar logic in the design of their analysis, so it’s not completely impossible for them to have made correlated mistakes. Still, this is far from plausible, so the onus will be on CDF to directly pinpoint an error in their competitors’ work.

Even if the mistake is CDF’s, it’s worth noting that we still have no idea what exactly it might have been. A long chain of measurements and calibrations are required to determine the W boson mass at this level of precision (about one part in ten thousand). It would be great if the error within this chain could be tracked down, but no one may have the stamina to do that, and it is possible that we will never know what went wrong.

But the bottom line is that the discrepancy suggested by the CDF measurement was always a long shot. I don’t think many particle physicists are surprised to see its plausibility fading away.

African giant pouched rats proved adept at detecting four commonly trafficked products derived from endangered species including rhino horn and elephant ivory

On the SGU we recently talked about aphantasia, the condition in which some people have a decreased or entirely absent ability to imagine things. The term was coined recently, in 2015, by neurologist Adam Zeman, who described the condition of “congenital aphantasia,” that he described as being with mental imagery. After we discussed in on the show we received numerous e-mails from people with the condition, many of which were unaware that they were different from most other people. Here is one recent example:

“Your segment on aphantasia really struck a chord with me. At 49, I discovered that I have total multisensory aphantasia and Severely Deficient Autobiographical Memory (SDAM). It’s been a fascinating and eye-opening experience delving into the unique way my brain processes information.

Since making this discovery, I’ve been on a wild ride of self-exploration, and it’s been incredible. I’ve had conversations with artists, musicians, educators, and many others about how my experience differs from theirs, and it has been so enlightening.

I’ve learned to appreciate living in the moment because that’s where I thrive. It’s been a life-changing journey, and I’m incredibly grateful for the impact you’ve had on me.”

Perhaps more interesting than the condition itself, and what I want to talk about today, is that the e-mailer was entirely unaware that most of the rest of humanity have a very different experience of their own existence. This makes sense when you think about it – how would they know? How can you know the subjective experience happening inside one’s brain? We tend to assume that other people’s brains function similar to our own, and therefore their experience must be similar. This is partly a reasonable assumption, and partly projection. We do this psychologically as well. When we speculate about other people’s motivations, we generally are just projecting our own motivations onto them.

Projecting our neurological experience, however, is a little different. What the aphantasia experience demonstrates is a couple of things, beginning with the fact that whatever is normal for you is normal. We don’t know, for example, if we have a deficit because we cannot detect what is missing. We can only really know by sharing other people’s experiences.

For example, let’s consider color vision. Someone who is completely color blind, who sees only in shades of grey, would have no idea that they are not seeing color, or that color exists as a phenomenon, except for the fact that other people speak of the fact that they perceive this thing called color. Even then it may take time as they grow to realize that other people are experiencing something they are not. But if they lived in a world with color-blind people, they would never know what they are missing.

This also relates to the old question – is what I experience as “red” the same thing that you experience as “red”? Is there any way we can know? We can only infer from indirect evidence. It’s likely that people experience colors similarly since we tend to associate the same emotions and feelings to those colors, but of course that could also be learned. However, there is no reason to assume our color experiences are identical. There are likely differences in vibrancy, contrast, shading, and other details. Also there are many people who are partially color blind (like me – I have a deficit in red-green distinction). I would never ever know, however, that my color vision was different than most people were it not for those tests we were forced to take where we try to see the number in the circles.

Similarly, if  you cannot form visual mental representations in your mind, you might assume everyone is that way. Several people with aphantasia have told me that when other people talked about “seeing” things in their mind, they assumed it was a metaphor. They had no idea other people were literally seeing an image in their mind.

Sometimes even the objective lack of a sensory experience might be entirely unknown to the person. For example, people who are born with a decrease in sensation because of a disorder of their nerves do not know this. Whatever sensation they have is normal for them. So they don’t complain of numbness, even though on exam they have a profound decrease in sensation (that’s how we know its congenital and not acquired).

We should, I think, extrapolate from this experience. There are likely countless ways in which our brains differ from each other in how they construct our subjective experience of reality, our abstractions, our emotional worlds, and our sensory perceptions. These are all brain constructs, dependent on the particulars of networks and nodes in the brain, how they connect, and how they function. We cannot get outside of this – this is who and what we are.  This is why neuroscientists have moved toward the concept of “neurodiversity” – understanding the full diversity of how different human brains function. There may be a “typical” brain, in one or more aspects, but there is also lots of diversity. We also should not automatically pathologize this diversity and assume anything not typical is a “disorder” or even worse, a “disease.” Mostly biological diversity is a matter of different tradeoffs.

Even when we recognize that some forms of neurodiversity may quality as a “disorder”, meaning that there are demonstrable objective negative outcomes, sometimes this is very context dependent. They may only have negative outcomes because neurotypicals have designed society to best suit them.  They may be on the short end of the tradeoffs, but that is not an inherent reality, just a societal choice.

Even more fascinating to me is to think about the universal human neurological experience. In other words – what do humans lack, or in what ways is human experience of reality idiosyncratic? Just like those with aphantasia, we likely will never know – not until we encounter other intelligent species who experience reality differently. If we are even able to sufficiently communicate with them, we may find their realities are very different from our own. Until then we may not know what it truly means to be human.

The post Subjective Neurological Experience first appeared on NeuroLogica Blog.

We are finally untangling the ancient history of the cactus family, revealing some surprising forces that shaped these plants – ­­­­­­and prompting concern for their future

Exoplanets in binary star systems usually orbit both stars, but astronomers have now spotted three planets orbiting one or the other star in a pair

Dwarf planet Ceres is the largest planetary body in the Asteroid Belt. For a long time, scientists thought it was born in the outer solar system and then migrated to its present position. Some evidence for that origin lies in extensive surface deposits of ammonium-rich materials on the Cerean surface.

Some of those bright, white and whitish-yellow deposits are found in impact craters on Ceres. Researchers suspect they are the remnants of a brine that seeped to the surface from a liquid layer between the mantle and crust. When impacts whacked the planet, they altered its surface. They also dug up and splattered material from the brine layer. Images and observational data from NASA’s Dawn mission of an impact region called Consus Crater also show bright yellowish-white deposits. Now, thanks to a deeper analysis of Dawn data, their presence could point to Ceres’s origin in the Asteroid Belt.

NASA’s Dawn spacecraft captured this approximately true-color image of Ceres in 2015 as it approached the dwarf planet. Dawn showed that some polar craters on Ceres hold ancient ice, but new research suggests the ice is much younger. Image Credit: NASA / JPL-Caltech / UCLA / MPS / DLR / IDA / Justin Cowart Peeping Inside Ceres

Ceres is classified as a dwarf planet and its rocky component is very similar to that of carbonaceous chondrite asteroids. At least a quarter of its mass is water ice. The surface is pretty complex, consisting of carbon-rich rocks and something called ammoniated phyllosilicates. Those are minerals that include such familiar substances as talc and mica. There’s also evidence of water ice in various surface regions.

This dwarf planet is an active world, with most of its activity driven by cryovolcanism. The surface has been gardened by impacts. The thick outer crust lies over a salt-rich liquid (that brine layer) and a muddy mantle. There’s a lot of evidence to suggest that the concentration of ammonium is greater in deeper layers of the crust. The few places on the surface of Ceres where those obvious yellowish-bright patches show up are in and near Consus Crater and also within other deep craters.

Planetary scientists have long wondered about exactly where Ceres formed. If it formed in the outer Solar system, then it must have migrated into position billions of years ago. If it formed in place, then that raises the question of how it could have become enriched with the icy ammonium-rich materials.

A cutaway showing the surface and interior of dwarf planet Ceres. Thick outer crust (ice, salts, hydrated minerals) Salt-rich liquid (brine), and rock “Mantle” (hydrated rock). Courtesy: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA Clues to Ceres’s Birthplace

Why the differing suggestions about where Ceres formed? Let’s look more deeply at those ammonium-rich deposits for an answer. They tend to form in very cold environments. That’s why people assumed that Ceres formed in the outer Solar System. That’s where frozen ammonium ice is most stable. In warmer environments (such as closer to the Sun), it evaporates. So, it makes sense to think that Ceres formed our where it was colder and then somehow migrated to the Asteroid Belt.

However, if the ice was part of a rocky planetesimal, the location might not matter so much. Inside the rock, the ice would be insulated from solar heating. Such world-forming materials exist closer to the Sun, and certainly out at the location of the Asteroid Belt. So, if they coalesced to form Ceres in situ, their encased ices would have contributed to the subsurface brine layer that today feeds the cryovolcanism. Impacts punching through the surface would release the brine, as well.

Connecting the Dots

A team led by Andres Nathues and Ranjan Sarkar (both Dawn mission scientists), zeroed in on materials sprayed across the surface in the area of Consus Crater. It lies in Ceres’s southern hemisphere and stretches across 64 kilometers (~39 miles). The crater walls are about 4.5 kilometers (~3 miles) high and parts of them are eroded. There’s a smaller crater inside on the eastern half of Consus. Its edges appear to be “painted” with speckles of bright yellowish material, which is also spattered out nearby.

Further analysis of the Dawn data ties the ammonium on the surface with the salty brine from Ceres’ interior. Cryovolcanic activity on this world brings the ammonium-rich brine up toward the Cerean surface. Once there, it seeps into the crust, according to Andreas Nathues, former lead investigator for the Dawn mission. “The minerals in Ceres’ crust possibly absorbed the ammonium over many billions of years like a kind of sponge,” said Nathues.

Nathues and others argue that the dwarf planet’s origin does not necessarily have to be in the outer Solar System simply based on the presence of those ammonium-rich deposits. As mentioned above, they could have been part of the planetesimals in the Asteroid Belt that coalesced to build Ceres. Once it formed, Ceres experienced impacts and cryovolcanism and those actions produced the surface deposits we see today.

Evidence from the Craters

Consus Crater itself was “dug out” between 400 and 500 million years ago by a huge impact. That event exposed material from the deep, particularly the ammonium-rich layers below Consus Crater. A later impact about 280 million years ago created the smaller crater inside. The yellowish-bright speckles to the east of the smaller crater are material ejected by the second event. If those materials always existed inside Ceres, then that supports the idea this dwarf planet formed where it is now, rather than out at the edge of the Solar System. That’s where the impacts become important, since that action exposed deeper layers, according to Dawn researcher Ranjan Sarkar.

“At 450 million years, Consus Crater is not particularly old by geological standards, but it is one of the oldest surviving structures on Ceres,” Sarkar said. “Due to its deep excavation, it gives us access to processes that took place in the interior of Ceres over many billions of years, and is thus a kind of window into the dwarf planet’s past.”

For More Information

Dwarf Planet Ceres: Origin in the Asteroid Belt?
Consus Crater on Ceres: Ammonium-enriched Brines Exchange with Phylosilicates?

The post Actually, Ceres Might Have Formed in the Asteroid Belt After All appeared first on Universe Today.